doing s4 to s5 n/a swap
 

will my s4 injectors work with an s5 ecu or is there an impedance difference in the electrical?

The ECU is irelivant.

The S5 harness is setup for high imp.

S4 harness <jun87 use high imp.

Injectors packaged in cars <jun87 are high imp.

Jan 87 and up, not June 87 and up.

June 87 and up are 88 model year cars. Mazda changed the impedence on the 87.5 models

icemark knows all! but anyways, i've done the swap and it isn't toooo hard. if u know what u are doing with the wiring then it goes alot easier

Thanks for your alls help.